1. Fossil Evidence of Evolution
6.1

2. The Fossil Record
Fossils are the remains or evidence of once-living organisms.
Fossil Record is made up of all the fossils ever discovered on Earth.
The Fossil Record is not complete.
Shows all species have changed over time.

3. Fossil Formation Rare conditions are required for a fossil to from.
Several ways fossils can form:
*Mineralization
*Carbonization
*Molds & Casts
*Trace Fossils
* Original Material

4. Determining a Fossil’s Age
Scientists cannot date most fossils directly.
Instead, they date the rocks the fossils are embedded inside.
Relative Dating- determine the relative order in which rock layers were deposited. (bottom layers are the oldest).
Absolute Dating- using radioactive decay, unstable isotopes in rocks change into stable isotopes over time.
Absolute dating is more precise than relative dating.

6. Fossils Over Time
Geologic Time Scale is a chart that divides Earth’s history into different time units.
Eons- longest time units ( 4 eons)
Eras- eons are divided into eras (3 eras)
Fossils were used to mark time.
Different rock layers contain different types of fossils.

8. Extinctions
Occurs when the last individual organisms of a species dies.
Mass extinctions occurs when many species becomes extinct with a few million years or less.
5 mass extinctions have occurred so far.
Environmental changes can cause extinctions.
Sudden changes can happen quickly, while gradual changes occur over time.

9. Extinctions and Evolution
Each species on Earth depends on other species.
Species must adapt to continue on.
Biological evolution is the change over time in populations of related organisms.
Several species have a common ancestor.